Nerve tissue in the context of Action potential

In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue. Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system.

An organ's tissues are broadly classified into parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland tissue that produces hormones is the parenchyma, while the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and remove metabolic wastes, and the connective tissues that provide structure, placement, and anchoring. The primary tissues that form an organ generally have common embryologic origins, often arising from the same germ layer. Organs are present in most multicellular organisms. In single-celled organisms such as eukaryotes, the functional analogue of an organ is an organelle. In plants, there are three main organs.The number of organs in any organism depends on the definition used. There are approximately 79 organs in the human body; the exact number remains debated.

Luigi Rolando (16 June 1773, Turin – 20 April 1831, Turin) was an Italian anatomist known for his pioneering research in brain localization of function.

He studied medicine in Turin, later continuing his education in Florence, where he studied engraving, drawing, anatomical dissection, and conducted microscopic investigations of nerve tissue. From 1804 he was a professor at the University of Sassari, and in 1814 was appointed professor of anatomy at the University of Turin.

Neuroblastoma (NB) is a type of cancer that forms in certain types of nerve tissue. It most frequently starts from one of the adrenal glands but can also develop in the head, neck, chest, abdomen, or spine. Symptoms may include bone pain, a lump in the abdomen, neck, or chest, or a painless bluish lump under the skin.

Typically, neuroblastoma occurs due to a genetic mutation occurring in the first trimester of pregnancy. Rarely, it may be due to a mutation inherited. Environmental factors have not been found to be involved. Diagnosis is based on a tissue biopsy. Occasionally, it may be found in a baby by ultrasound during pregnancy. At diagnosis, the cancer has usually already spread. The cancer is divided into low-, intermediate-, and high-risk groups based on a child's age, cancer stage, and what the cancer looks like.